JP2011064187A - Reciprocating engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocating engine in which the sliding frictional resistance is reduced between a piston and a cylinder by resisting thrust force arising from a tilt of a connecting rod to support the piston with the piston spaced from the cylinder by the gas pressure introduced into an annular gas chamber. <P>SOLUTION: In the reciprocating engine 1, a piston ring 26 is provided in parallel to an upper surface 3A of the piston and a piston ring 27 is provided aslope to the reciprocating direction of the piston 2. A portion between the piston rings 26, 27 is formed widely in the thrust applying direction 12 and narrowly in progression toward a direction 13 opposite to the thrust applying direction. The center of the piston pin 10 is biased to the thrust applying direction 12 in relation to the center of the piston. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement of a piston engine.

  More specifically, the present invention relates to the combustion above the piston in the annular gas chamber formed by the outer periphery of the second land (second land) of the piston, the inner surface of the cylinder, the first piston ring and the second piston ring. The present invention relates to a reciprocating engine in which high-pressure gas is introduced and a piston is floated and supported from a cylinder on the thrust side by the introduced gas pressure to reduce frictional resistance between the piston and the cylinder.

  Both Patent Document 1 and Patent Document 2 are techniques for reducing the friction loss between the piston and the cylinder on the thrust side due to the thrust force acting on the piston. The technology described in these documents is a piston having a piston upper body composed of an upper surface of a piston that receives combustion pressure and a land portion to which a piston ring is attached, and a skirt formed on the lower side of the piston upper body. An annular gas chamber is formed in the second land portion between the first piston ring and the second piston ring mounted on the outer peripheral surface of the upper body so as to be wide on the thrust side and gradually narrow toward the anti-thrust side. When a plurality of recesses are formed in the upper part on the thrust side of the inner surface of the cylinder and the piston is located at or near the top dead center, the high pressure gas above the piston is passed through the recess to the annular gas chamber. And a reciprocating engine in which the piston is supported from the thrust side by the high-pressure gas flowing into the gas chamber.

  That is, the piston is lifted from the cylinder and supported by the gas pressure introduced into the annular gas chamber against the thrust force (side pressure) generated by the inclination of the connecting rod, and the sliding friction resistance between the piston and the cylinder is reduced. Reciprocating engine.

International Publication No. WO92 / 02722 International Publication No. WO 2004/079177

  In the conventional piston described above, the piston pin is eccentric from the piston center line to the anti-thrust side. For this reason, when the piston reaches top dead center in the compression stroke, the piston upper body is easily separated from the inner surface of the cylinder on the anti-thrust side, and the combustion gas is discharged to the top land on the anti-thrust side of the piston in the next explosion expansion stroke Pressure acts strongly. For this reason, even if the gas pressure is introduced into the annular gas chamber from the thrust side, the piston cannot be sufficiently floated, and the frictional resistance on the thrust side is not sufficiently reduced. Therefore, the present invention eliminates the above defects.

  In a piston comprising a piston upper body comprising a piston upper surface that receives combustion gas pressure and a land portion to which a piston ring is attached, and a skirt formed on the lower side of the piston upper body, the inner surface of the cylinder and the piston upper body An annular gas chamber surrounded by the outer peripheral surface of the second land portion, the first piston ring, and the second piston ring is formed, and a plurality of recesses are formed in the upper part of the thrust side of the inner surface of the cylinder, resulting in an explosion. When the piston is located at or near the top dead center in the combustion stroke, the high pressure gas above the piston flows into the upper annular gas chamber through the recess, and the piston is supported from the thrust side by the high pressure gas flowing into the gas chamber. In the reciprocating engine that is lowered, the first piston ring is provided in parallel to the upper surface of the piston, and the second piston ring is Provided in a slanted manner with respect to the reciprocating direction of the ston, and the width between the first piston ring and the second piston ring is wide on the thrust side and gradually narrows toward the anti-thrust side. Is a reciprocating engine eccentric to the thrust side with respect to the piston center.

  Since the piston pin of the piston is eccentric to the thrust side from the piston center line, even when the piston reaches top dead center during the compression stroke, the piston upper body of the piston is less separated from the inner surface of the cylinder on the anti-thrust side. The influence of the combustion gas pressure acting on the top land on the thrust side is small. For this reason, the piston is supported by the high-pressure gas introduced into the annular gas chamber from the thrust side, and is sufficiently floated from the cylinder inner surface to reduce the friction between the cylinder inner surface and the piston.

It is longitudinal section explanatory drawing of the example of embodiment of this invention. It is operation | movement explanatory drawing of the example shown in FIG. It is explanatory drawing of the piston of the example shown in FIG.

  Embodiments of the present invention will be described below with reference to examples shown in the drawings.

  1 to 3 show an embodiment of a reciprocating engine of the present invention.

  1 to 3 show a piston 2 of a reciprocating engine 1 of the present embodiment. The piston 2 includes a piston upper body 8 including a piston upper surface portion 3 that receives combustion pressure and a land portion 7 having piston ring grooves 4, 5, and 6, and a skirt portion 9 formed below the piston upper body 8. And a pin boss portion for supporting the piston pin 10. The land portion 7 also refers to the outer peripheral surface 16 of the piston upper body 8. Hereinafter, the land portion 7 is referred to as the outer peripheral surface 16 of the piston upper body 8. In the piston 2, 12 indicates the thrust side, and 13 indicates the anti-thrust side.

  The piston 2 is formed such that the piston upper body 8 is decentered e on the anti-thrust side 13 with respect to the center line 14 of the piston 2. Reference numeral 15 denotes a center line of the piston upper body 8. As shown in FIG. 3, the piston 2 is in an upright posture, and the outer peripheral surface 16 of the piston upper body 8 and the outer peripheral surface 17 of the skirt portion 9 are formed on the vertical line 18 on the anti-thrust side 13. Yes.

  On the other hand, on the thrust side 12, the outer peripheral surface 19 of the piston upper body 8 is located on the inner side from the vertical line 21 passing through the outer peripheral surface 20 of the skirt portion 9, and there is a gap 22.

  In particular, as shown in FIG. 3, the piston 2 is arranged such that the center 11 of the piston 10 is eccentrically e2 on the thrust side 12 with respect to the piston center line 14. Since the piston 2 is shaped as described above, as shown in FIGS. 1 and 2, when the piston 2 is incorporated in the cylinder 23 and is in the upright posture, the outer circumferential surface 16 of the piston upper body 8 and the skirt are on the anti-thrust side 13. Both the outer peripheral surface 17 of the part 9 and the inner surface 24 of the cylinder 23 are in contact with each other. On the other hand, on the thrust side 12, a clearance (clearance) 25 exists between the outer peripheral surface 19 of the piston upper body 8 and the inner surface 24 of the cylinder 23. Piston rings 26 and 27 for compression are incorporated in the piston ring grooves 4 and 5 of the piston upper body 8. That is, the first piston ring 26 is incorporated in the first piston ring groove 4 closest to the piston upper surface 3, and the second piston ring 27 is incorporated in the second piston ring groove 5 closest to the next. Yes. Of course, the first piston ring 26 is a top ring, and the second piston ring 27 is a second ring. Of course, an oil scraping ring 28 is incorporated in the third piston ring groove 6.

  The first piston ring groove 4 in which the first piston ring 26 is incorporated is formed in parallel to the piston upper surface 3A. The second piston ring groove 5 in which the second piston ring 27 is incorporated is formed so as to incline downward from 2 ° to 5 ° toward the thrust side 12. That is, the second piston ring groove 5 is formed such that the distance D between the first piston ring groove 4 and the piston upper surface 3A is wider on the thrust side 12 and gradually narrower toward the anti-thrust side 13. Yes.

  Therefore, the second piston ring 27 has a wider distance D1 (second land portion 30) between the first piston ring 26 parallel to the piston upper surface 3A on the thrust side 12 and toward the anti-thrust side 13. Increasingly narrow.

  As shown in FIG. 1 and FIG. 2, in the state where the piston 2 is incorporated in the cylinder 23, the piston 2 includes the outer peripheral surface of the second land portion 30 of the piston upper body 8, the inner surface 24 of the cylinder 23, and the first piston ring. An annular gas chamber 31 surrounded by 26 and the second piston ring 27 is formed.

  As described above, since the second land portion 30 is wide on the thrust side 12 and gradually narrows toward the anti-thrust side 13, the annular gas chamber 31 is also wide on the thrust side 12 and is anti-thrust. It gradually becomes narrower toward the side 13.

  The reciprocating engine 1 introduces the high-pressure gas 38 above the piston 2 into the annular gas chamber 31 and holds the introduced high-pressure gas 39 in the initial stage of the combustion expansion stroke.

  As shown in FIGS. 1 and 2, the cylinder 23 has a plurality of recesses 34 (three to four) along the circumferential direction 35 on the inner surface 24 of the thrust side 12 at the upper portion 33. , Provided side by side. The recesses 34, 34, 34 are deep from the cylinder inner surface 24 and are formed in a hollow shape. Although these recesses 34, 34, and 34 will be described later, they serve as gas pressure passages. The positions of these recesses 34, 34, 34 are such that when the piston 2 is in the vicinity of the top dead center, the first piston ring 26 of the piston 2 is passing over the recesses 34, 34, 34. It has been established.

  Thus, when the piston 2 is in the vicinity of the top dead center and the first piston ring 26 is passing over the recesses 34, 34, 34, the respective recess spaces of the recesses 34, 34, 34 are provided. 36, 36, 36 and the outer peripheral surface of the first piston ring 26 become a passage, the combustion chamber 37 above the piston 2 communicates with the annular gas chamber 31 of the piston 2, and the high-pressure gas 38 above the piston 2. Flows into the annular gas chamber 31 as indicated by an arrow 41.

  Since the piston 2 of the piston 2 is eccentric from the piston center line 14 to the thrust side 12 when the engine is in operation from the compression stroke to the explosion / expansion stroke, the piston 2 of the piston 2 is eccentric to the thrust side 12. The piston upper body 8 is less separated from the cylinder inner surface 24 on the anti-thrust side 13, and therefore, the influence of the combustion gas pressure above the piston 2 on the land (top land) on the anti-thrust side 13 of the piston 2 is small. At the same time, when the first piston ring 26 passes through the recesses 34, 34, 34 of the cylinder 23 at the beginning of the explosion / expansion stroke, the high-pressure gas 38 in the combustion chamber 37 passes through the recess spaces 36, 36, 36. It is introduced into the annular gas chamber 31. This annular gas chamber 31 has a much larger pressure receiving area on the thrust side 12 than the anti-thrust side 13 and the high-pressure gas 39 is introduced from the thrust side 12. 23 is lifted and supported from the inner surface 24 of 23, and the expansion stroke is lowered.

DESCRIPTION OF SYMBOLS 1 Reciprocating engine 2 Piston 4 1st piston ring groove 5 2nd piston ring groove 6 3rd piston ring groove 7 Land part 8 Piston upper body 9 Skirt part 10 Piston pin 11 Pinton center 12 Thrust side 13 Anti-thrust side 14 Piston center Line 15 Centerline of piston upper body 16 Outer surface of piston upper body 17 Outer surface of skirt part 18 Vertical line 19 Outer surface of thrust side piston upper body 20 Outer surface of thrust side skirt part 21 Thrust side vertical line 22 Gap 23 Cylinder 24 Inner surface 25 Clearance
26 1st piston ring 27 2nd piston ring 28 Oil scraping ring 30 2nd land part 31 Annular gas chamber 33 Upper part 34 Recess 35 Circumferential direction 36 Recessed space 37 Combustion chamber 38 High pressure gas 39 High pressure gas 41 Arrow

Claims (1)

  In a piston comprising a piston upper body comprising a piston upper surface that receives combustion gas pressure and a land portion to which a piston ring is attached, and a skirt formed on the lower side of the piston upper body, the inner surface of the cylinder and the piston upper body An annular gas chamber surrounded by the outer peripheral surface of the second land portion, the first piston ring, and the second piston ring is formed, and a plurality of recesses are formed in the upper part of the thrust side of the inner surface of the cylinder, resulting in an explosion. When the piston is located at or near the top dead center in the combustion stroke, the high pressure gas above the piston flows into the upper annular gas chamber through the recess, and the piston is supported from the thrust side by the high pressure gas flowing into the gas chamber. In the reciprocating engine that is lowered, the first piston ring is provided in parallel to the upper surface of the piston, and the second piston ring is Provided between the first piston ring and the second piston ring so as to be wide on the thrust side and gradually narrow toward the anti-thrust side. Is a reciprocating engine that is eccentric to the thrust side with respect to the piston center.

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